1. Field of the Invention
The present invention relates to an electrophoresis apparatus used for rapidly and precisely analyzing a sample.
2. Description of the Prior Art
Conventionally, electrophoresis apparatuses are used for analyzing proteins and nucleic acids in organisms, and very small amounts of substances contained in foods and chemicals (see, e.g., Japanese Patent Laid-Open No. 11-326274).
In such an electrophoresis apparatus, as shown in FIGS. 11A through 11C, an introducing passage 111 and analyzing passage 110, which have a very small cross section (e.g., a width of about 100 micrometers×a depth of about tens micrometers), are formed so as to be perpendicular to each other. In the electrophoresis apparatus shown in FIGS. 11A through 11C, an electrophoresis buffer 114 is filled in the introducing passage 111 and analyzing passage 110, and a sample 113 serving as an object to be analyzed is introduced into the introducing passage 111 from one end thereof. Then, as shown in FIG. 12A, the sample 113 is moved by electrophoresis from the one end of the introducing passage 111, in which the electrophoresis buffer 114 is filled, to beyond a cross-portion 108, in which the introducing passage 111 crosses the analyzing passage 110 to be communicated therewith, so that the sample 113 is expanded in the introducing passage 111 (see FIG. 12A). Then, a very small amount of sample 113a positioned in the cross-portion 108 is separated from the other part of the sample 113 in the introducing passage 111 to be moved in the analyzing passage 110 by electrophoresis. Thus, the very small amount of sample 113a containing plural kinds of components is separated into a plurality of bands (a group of materials) in the analyzing passage 110 since they have different electrophoresis speeds (traveling speeds of components due to electrophoresis) in accordance with the difference in molecular weight or the like between the components. Then, if the analyzing passage 110 is irradiated with light from an optical system for analysis, fluorescence is emitted from the fluorescent marker of the sample 113a to be detected by a detecting means (e.g., a light receiving element) to analyze the sample 113a. 
However, if the introducing passage 111 and the analyzing passage 110 are formed so as to be substantially perpendicular to each other as the above described conventional apparatus, when a very small amount of sample 113a in the cross-portion 108 is separated to be moved in the analyzing passage 110 by electrophoresis, there are some cases where a part of the sample 113a near the wall surface of the analyzing passage 110 is deformed so as to greatly leave its trails 115, so that adjacent bands overlap with each other to deteriorate performance in the separation of the components (bands) of the sample 113a. 